1. Field of the Invention
The present invention relates to a grommet for wire harness and is specifically made of rubber or elastomer to be externally fitted to a wire harness to be wired in an automotive vehicle and mounted in a through hole of a vehicle-body panel from being detached from the through hole particularly by increasing a retention force in the through hole.
2. Description of the Related Art
Conventionally, a large number of grommets for wire harness of this type have been proposed. In many cases, these grommets are designed to improve waterproof performance of a wire harness inserted through the grommet, reduce an insertion force at the time of mounting the grommet into a through hole of a vehicle-body panel and make the wire harness easily bendable in the case of bending and wiring the wire harness from a position drawn out from the grommet mounted in the through hole of the vehicle-body panel.
For example, to reduce an insertion force of a grommet into a through hole and make a wire harness easily bendable, there has been proposed a grommet 100 shown in FIGS. 6(A) and 6(B) in Japanese Unexamined Patent Publication No. H11-63313. This grommet 100 is formed such that a small-diameter cylindrical portion 101 through which a wire harness 110 is tightly inserted and a large-diameter cylindrical portion 103 including an annular recess 104 to be fitted to a through hole 109 of a vehicle-body panel 108 are connected via a radially extending wall portion 102, and an elastic portion 105 projecting toward the large-diameter cylindrical portion 103 in parallel to an axial direction of the grommet 100 is provided at a position where the wall portion 102 is connected to the small-diameter cylindrical portion 101. Reinforcing ribs 107 are provided in a recess 106 of the elastic portion 105 at the small-diameter cylindrical portion 101 side.
The grommet 100 can increase its restoring force after the deformation of the elastic portion 105 by the reinforcing ribs 107. However, the reinforcing ribs 107 make the wire harness 110 hard to bend when the wire harness 110 drawn out from the grommet 100 mounted in the through hole needs to be steeply bent and wired, and reduce deformability of the grommet 100 at the time of mounting the grommet into the through hole, thereby causing problems such as a reduction in an effect of reducing an insertion force into the through hole.